POLINI 102 cc CYLINDER KIT Ø 55 mm - VESPA 50 - APE 50

This Polini cast iron cylinder kit Ø 55 mm with 102 cc displacement is designed to significantly improve the performance of the original engine on Vespa 50 and Ape 50, while maintaining reliability, strength and long-term durability. It is compatible with Vespa 50 N, 50 L (Lusso), 50 R (Rinnovata), 50 Special, 50 Revival, 50 PK, 50 PK S, 50 PK XL and Ape 50.

Compared to the standard cylinder, this kit features revised transfer ports, engineered to provide increased performance and improved throttle response, delivering approximately 8.7 HP. Power delivery is smoother and stronger, with good torque in the low and mid-range.

The cylinder can be installed without replacing the original 43 mm stroke crankshaft, making installation simple and straightforward. The kit is supplied complete with cylinder head and gaskets, ready for assembly, with no need for specific machining on the crankcases.

The cast iron construction and Polini machining ensure high mechanical strength, excellent torque and controlled fuel consumption, providing reliable and consistent performance across all operating ranges. For further performance gains, a racing crankshaft can be fitted, although the original crankshaft remains suitable.

Below are baseline carburetion settings, intended as a starting point for tuning and to be adjusted according to altitude, exhaust system and engine configuration:

SHB 16.16: main jet 66–68
SHB 19.19: main jet 80–82
PHBL 24: main jet 72–76 – idle jet 50 – atomizer AQ264 – needle D22 – slide 40 – starter jet 60
PHBL 24 reed-valve: main jet 100–102 – idle jet 64 – atomizer AQ264 – needle D22 – slide 40 – starter jet 60

Recommended spark plugs: NGK B8ES, Bosch W4CC, Denso Iridium IW27, with ignition timing set to 17°.

Additional performance improvements can be achieved by fitting a larger carburetor, variable-advance electronic ignition, longer gear ratios, reinforced clutch and a suitable exhaust system, depending on the intended use.

For further information or assistance, the Emporio dello Scooter customer service is always available.

Product intended for racing and sporting use only. Not homologated for use on public roads.